Intact Audio

Thanks Stephie, just downloading now to try.

Thanks muchly!

Brilliant, thanks Stephie.

Hi Stephie, is there any chance of a model for the 46? Been wondering about that one for a while...

ETF was great, loved your presentation, JC! That pre didn;t sound too bad, either.

Some photos from the event, here:

http://s108.photobucket.com/albums/n15/ ... o/ETF2010/

Cheers,
Pete

So here's the response I got after changing the coupling cap (C1) to 1uF, The 700p (C2) to 7p and the 7.6H inductor (L2) to 8.7H.

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I simmed this a while back and found the same. It needs a few "corrections". I'll try and find the ASC...

Ooh! Nice one Dave. A couple of years ago I built the Shishido 801A amp (as published in SP10) but with different filament supplies. I managed to luck into a complete set of iron on eBay. The Tango interstages (10672, I think?) were custom made with something like a 1:0.8 step-down. The data sheet r...

I really like that.

Happy New Year folks!

Anyone had any thoughts on this over Christmas?

Some info on 'k' here:

http://www.burnyourbonus.info/sci.elect ... d1748.html

There's a mention that k=(1-Llp)/Lp

I'm still digesting the rest of it!

Hmmm... good points. I confess, I hadn't tried changing K, but I see what you mean - changing it from 1 to 0.998 (0.2%) changes things pretty spectacularly! While changing the leakage inductances by 1% doesn't seem to affect things much at all. Bugger.

<goes off to scratch head>

I think the 'k' factor is simply a shorthand way of expressing the leakage inductance (and perhaps other parameters) but in this case we're modelling them directly so we don't need to account for it elsewhere. I think it would be useful to added semi-realistic capacitances so that we're accurate as ...

Thanks Dave, that looks like an easier load. I wonder if it's possible to tweak the values to help that in the first case, but perhaps it is what it is... I was kind of holding off modelling capacitances until we had the basis circuit, but given the sensitivity to source impedances, it doesn't reall...

Hiya Dave, hey guys. Lars, I ran your version and the pic is below. When I put a 4700uf bypass across Pete's Rx3 I saw a similar response. Pete, what is the rational between the progression between RX1 and RX3? what purpose do the extra parts in Rx3 serve? RX1 was just a first step using the inverse...

Thanks Lars!

Hi Guys, Well, the only LRiaa design I know of (from Steve B) uses two IT's in series. This design is simpler than that which I like. Why the leakage inductance should be in the transformer is a good question. The way I see it is that this 'virtual' component might well be a 'perfect' one as long a...

Hi guys, I'm not and expert on modelling, so I don't know if that's the correct model for this. The text talks about the time constants coming from the leakage inductance which itself relies on lossy coupling. I'm not sure how the leakage inductance and 'k' factor should be considered in SPICE. My q...

Thanks guys! NC, can we not simply model it as a perfect transformers + leakage inductances? I did a couple - RX01 is just a model using voltage sources to model the transformers and RX03 is an attempt at a practical circuit using 437A. I;m not sure whether these are complete and we need to account ...

Ah, I figured you would already be onto it Dave! :D These were the pages which set me off, which seem to indicate a production piece: http://www.audionote.co.uk/news/article_pre_06-06_m9.shtml http://www.audionote.co.uk/products/preamp/m9_phono_01.shtml I'm sure win true Audio Note style it's mind-b...

I've been at phono stuff recently and was reading that Audio Note are using Transformer RIAA correction. CV pointed me in the direction of this (I assume the Audio Note solution is similar to this): http://www.aml.nm.ru/RX_corrector_eng.htm Looks like an interesting way of doing things. Does anyone ...

Andrew wrote:Oh, that's a pity, it would have been something else to try.

Whoops I meant to ask if you had tried referencing C11 to 'k' rather than ground?

cheers,

-- Andrew

Interesting, I might try that, thanks!

Hi Andrew, unfortunately that's not an option with these as the caps are apparently only rated for 63V in these modules.

The long term plan is to probably re-do this when I've had a chance to do more sims and pick a network impedance value I'm happy with.

Hi Andrew, this is what I actually built (not with D3a though).

I loaded the 10k network with 12k and the tube with 5k. This means that the tube will actually see about 3.5k. SPICE seemed to think this was ok. I did find the 10k network to be more sensitive to source and load impedances than the 600 for some reason (possibly I'm doing something wrong, can't thin...

Well, I tried the 448As as Tetrodes into some Silk 10k modules I had lying about. I loaded the tubes with 5k and the network with 12k at the other end. This gives a good response in SPICE. Overall gain is good at over 40dB. Subjectively, it sounds very, very good. I've also simmed it using a cascode...

I did sim this in SPICE, using a D3A pentode as first stage and a triode second stage - it comes at out about 56dB gain! So gain is not really an issue. I wonder if it even needs a second stage... Is that for the 7k3? Sounds roughly right. I get 50db or so with the 1k5 and the right valves, second ...

Agreed, however, a step down and a high gm triode would drive a 7k-ish LCR, I would have thought. Ageing would still be an issue, wouldn't it? Yeah, using a triode to set source Z is a non starter in my book for that very reason, but a the down and a fixed load should ameliorate most of that, which...

Thanks Andrew, presumably a high-Gm triode would still be quieter though, because it lacks the other noise sources of the pentode? This seems a very elegant way to use the LCRs. I was just wondering as Morgan Jones goes into noise in his book and discards pentodes as being too noisy. I've never trie...

The only worry for me using a pentode in the first stage would be noise (specifically partition noise). Does anyone have a view on how much of an issue this is in practice?